1 files changed, 67 insertions, 0 deletions
diff --git a/utils/x11_make_greeting.c b/utils/x11_make_greeting.c
new file mode 100644
index 00000000..4efd8e83
--- /dev/null
+++ b/utils/x11_make_greeting.c
@@ -0,0 +1,67 @@
+/*
+ * Construct an X11 greeting packet, including making up the right
+ * authorisation data.
+ */
+
+#include "putty.h"
+#include "ssh.h"
+
+void *x11_make_greeting(int endian, int protomajor, int protominor,
+                        int auth_proto, const void *auth_data, int auth_len,
+                        const char *peer_addr, int peer_port,
+                        int *outlen)
+{
+    unsigned char *greeting;
+    unsigned char realauthdata[64];
+    const char *authname;
+    const unsigned char *authdata;
+    int authnamelen, authnamelen_pad;
+    int authdatalen, authdatalen_pad;
+    int greeting_len;
+
+    authname = x11_authnames[auth_proto];
+    authnamelen = strlen(authname);
+    authnamelen_pad = (authnamelen + 3) & ~3;
+
+    if (auth_proto == X11_MIT) {
+        authdata = auth_data;
+        authdatalen = auth_len;
+    } else if (auth_proto == X11_XDM && auth_len == 16) {
+        time_t t;
+        unsigned long peer_ip = 0;
+
+        x11_parse_ip(peer_addr, &peer_ip);
+
+        authdata = realauthdata;
+        authdatalen = 24;
+        memset(realauthdata, 0, authdatalen);
+        memcpy(realauthdata, auth_data, 8);
+        PUT_32BIT_MSB_FIRST(realauthdata+8, peer_ip);
+        PUT_16BIT_MSB_FIRST(realauthdata+12, peer_port);
+        t = time(NULL);
+        PUT_32BIT_MSB_FIRST(realauthdata+14, t);
+
+        des_encrypt_xdmauth((char *)auth_data + 9, realauthdata, authdatalen);
+    } else {
+        authdata = realauthdata;
+        authdatalen = 0;
+    }
+
+    authdatalen_pad = (authdatalen + 3) & ~3;
+    greeting_len = 12 + authnamelen_pad + authdatalen_pad;
+
+    greeting = snewn(greeting_len, unsigned char);
+    memset(greeting, 0, greeting_len);
+    greeting[0] = endian;
+    PUT_16BIT_X11(endian, greeting+2, protomajor);
+    PUT_16BIT_X11(endian, greeting+4, protominor);
+    PUT_16BIT_X11(endian, greeting+6, authnamelen);
+    PUT_16BIT_X11(endian, greeting+8, authdatalen);
+    memcpy(greeting+12, authname, authnamelen);
+    memcpy(greeting+12+authnamelen_pad, authdata, authdatalen);
+
+    smemclr(realauthdata, sizeof(realauthdata));
+
+    *outlen = greeting_len;
+    return greeting;
+}